Wilson did several worthwhile things while in office, but as far as I’m concerned the good he did is far outweighed by the bad.
He was an academic so he should have known better, in my opinion, but he was so intent on establishing his pie in the sky League of Nations (a good idea but one whose time hadn’t come) that he allowed the other nations to impose onerous penalties on Germany at the Paris Peace Conference. That was the first of two major blunders of the 20th century, and it led directly to conditions that gave rise to Hitler.
Plus, he was opposed to women’s suffrage and was an unrepentant racist.
As Wikipedia states:
Wilson was born and raised in the U.S. South by parents who were committed supporters of both slavery and the Confederacy. Academically, Wilson was an apologist for slavery and the Redeemers, and one of the foremost promoters of the Lost Cause mythology. Wilson was the first Southerner elected president since Zachary Taylor in 1848 and the only former subject of the Confederacy. Wilson’s election was celebrated by southern segregationists. At Princeton, Wilson actively dissuaded the admission of African-Americans as students. Several historians have spotlighted consistent examples in the public record of Wilson’s overtly racist policies and the inclusion of segregationists in his Cabinet. Other sources say Wilson defended segregation as “a rational, scientific policy” in private and describe him as a man who “loved to tell racist ‘darky’ jokes about black Americans.”
During Wilson’s presidency, D. W. Griffith’s pro-Ku Klux Klan film The Birth of a Nation (1915) was the first motion picture to be screened in the White House.
Oh, and then there’s this:
On receiving the Democratic nomination for President at Baltimore in 1912, he declared: “I am a Presbyterian and believe in predestination and election. It was Providence that did the work at Baltimore.” After the election he told William F. McCombs, chairman of the Democratic National Committee: “Before we proceed I wish it clearly understood that I owe you nothing.” Surprised, McCombs reminded him of his services during the campaign, but Wilson exclaimed: “God ordained that I should be the next President of the United States. Neither you nor any other mortal could have prevented that!”
— Presidential Anecdotes by Paul F. Boller Jr.
That would be enough for me to relegate him to the category of asshole.